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Fav 2 subset with 11 entries (Example in text has 9) |
- All, 50 screens
- Fav 1, 34 screens
- Fav 2, 9 screens
- Calendar, 13 screens
- Clocks, 27 screens
- Astro, 17 screens
- Radio, 12 screens
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Example of a speech signal which transitions from an unvoiced to a voiced sound |
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Weekly progress bar with Monday as day 1 in week 9 and yearly progress bar as of day 56 in the year. |
I got an unassembled QMX+ for Christmas this year, and here are pictures of it coming together. First the winding of toroids for the low-pass filters:
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Propagation of wave energy to distance d, 2d, 3d showing how the size of the surface that the energy spreads over increases in proportion to d², (2d)², and (3d)² |
This is very counterintuitive, because if one solves the wave equation, the amplitude of the solution is independent of frequency. The physics of the problem is that intensity just falls with distance squared according to how the surface of a sphere increases with the radius as shown in the figure.
The Friis formula used in link budgets says something else. It gives received power, Pr, as a function of transmitter power, Pt, receiver and transmitter antenna gains, Gr and Gt; wavelength, lambda, and distance, d:
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Envelope Elimination and Restoration, from Kahn 1952 |
In the QMX a single frequency signal is generated in the digital domain and then phase modulated (upper branch of figure). It then has a digital output stage with very high efficiency as it only switches between on and off. The output stage is amplitude modulated with the envelope signal from the lower branch.This gives a much more efficient power amplification than is possible with the three conventional methods.
How does it compare with other methods? In 1956, Donald K. Weaver, Jr. wrote a paper with title "A Third Method of Generation and Detection of Single-Sideband Signals".
Demo mode now has a choice of increase, decrease, or random next screen number (selectable in Secondary menu).
More languages selectable: {"en", "es", "fr", "de", "no", "se", "dk", "is"}. Any language with max 4 special letters in alphabet can be implemented.
Better accuracy:
Now runs on Adafruit Metro Express (M0). This makes it much faster for the Hebrew calendar in particular.
And some more minor fixes, see details on Github.